The low and high temperature thermoelectric properties of Sb doped Cu₂SnSe₃

The effect of Sb doping on the thermoelectric properties of Cu₂SnSe₃ was investigated. The Cu₂Sn_{1 - x}Sb_xSe₃ (0 ≤ x ≤ 0.04) compounds were prepared by solid state synthesis. The powder X-ray diffraction pattern of the samples showed a cubic structure (space group F43m). The electrical resistivity decreased with increase in Sb content up to x = 0.02, then it increased with further increase in x. The electrical resistivity data follows variable hopping model at low temperatures. The Seebeck coefficient for all the samples is positive and analysis of data confirms that the variable hopping process is operative at low temperatures. The thermal conductivity is found to decrease with increase in Sb concentration, presumably due to point-defect scattering as a result of Sb substitution. The highest value of figure of merit at 400 K is equal to 0.0137 for the sample Cu₂Sn_0.99Sb_0.01Se₃ which is about eight times greater than that of the pristine sample.